[PATCH 30/41] drm/i915: enable power wells on haswell init

[Eugeni Dodonov <eugeni.dodonov@intel.com>]

This attempts to enable all the available power wells during the
initialization.

Those power wells can be enabled in parallel or on-demand, and disabled
when no longer needed, but this is out of scope of this initial
enablement. Proper tracking of who uses which power well will require
a considerable rework of our display handling, so we just leave them all
enabled when the driver is loaded for now.

Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
---
 drivers/gpu/drm/i915/intel_display.c |   31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7daad41..0e06a29 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -9173,6 +9173,34 @@ static void i915_disable_vga(struct drm_device *dev)
 	POSTING_READ(vga_reg);
 }
 
+/* Starting with Haswell, we have different power wells for
+ * different parts of the GPU. This attempts to enable them all.
+ */
+static void intel_init_power_wells(struct drm_device *dev)
+{
+	struct drm_i915_private *dev_priv = dev->dev_private;
+	unsigned long power_wells[] = {
+		HSW_PWR_WELL_CTL1,
+		HSW_PWR_WELL_CTL2,
+		HSW_PWR_WELL_CTL4
+	};
+	int i;
+
+	mutex_lock(&dev->struct_mutex);
+
+	for (i = 0; i < ARRAY_SIZE(power_wells); i++) {
+		int well = I915_READ(power_wells[i]);
+
+		if ((well & HSW_PWR_WELL_STATE) == 0) {
+			I915_WRITE(power_wells[i], well & HSW_PWR_WELL_ENABLE);
+			if (wait_for(I915_READ(power_wells[i] & HSW_PWR_WELL_STATE), 20))
+				DRM_ERROR("Error enabling power well %lx\n", power_wells[i]);
+		}
+	}
+
+	mutex_unlock(&dev->struct_mutex);
+}
+
 void intel_modeset_init(struct drm_device *dev)
 {
 	struct drm_i915_private *dev_priv = dev->dev_private;
@@ -9190,6 +9218,9 @@ void intel_modeset_init(struct drm_device *dev)
 
 	intel_init_quirks(dev);
 
+	if (IS_HASWELL(dev))
+		intel_init_power_wells(dev);
+
 	intel_init_display(dev);
 
 	if (IS_GEN2(dev)) {
-- 
1.7.9.5